Air preheating combustion apparatus

ABSTRACT

A low emission combustion apparatus for a gas turbine engine employs vaporization of liquid hydrocarbon fuel to produce a mixture of vaporized fuel and primary or combustion air for a main combustion apparatus. The primary air is brought to a high enough temperature for vaporization of fuel by an air preheating combustor in which a relatively small part of the total fuel is burned. The preheating combustor operates at a relatively low temperature to avoid production of nitrogen oxides, and thus may produce some carbon monoxide. This, however, is burned in the main reaction zone, which operates at a higher temperature. Prevaporization of the fuel eliminates hot spots caused by fuel droplet combustion and thus promotes clean combustion. The fuel vaporizer comprises structure defining two concentric annular passages through which the air flows with swirl and in which the fuel is laid on the outer wall of each passage from a circumferential manifold. Fuel may be supplied to one or both manifolds.

United States Patent [191 Verdouw Dec. 9, 1975 AIR PREHEATINGCONIBUSTION APPARATUS Albert J. Verdouw, Indianapolis, Ind.

[22] Filed: Nov. 11, 1974 [21] Appl. No.: 522,683

[75] Inventor:

[52] US. Cl. 431/10; 60/3971; 431/11; 431/352 [51] Int. Cl. F23M 3/04[58] Field of Search 431/10, 352, 353, 215, 431/11; 60/3965, 39.71

[56] References Cited UNITED STATES PATENTS 2,621,477 12/1952 Powter eta1 60/3971 X 3,691,762 9/1972 Ryberg et al. 60/3971 X 3,859,787 1/1975Anderson et al. 60/3971 Primary ExaminerEdward G. Favors Attorney,Agent, or Firm Paul Fitzpatrick FUEL FUEL CONTROL [57] ABSTRACT A lowemission combustion apparatus for a gas turbine engine employsvaporization of liquid hydrocarbon fuel to produce a mixture ofvaporized fuel and primary or combustion air for a main combustionapparatus. The primary air is brought to a high enough temperature forvaporization of fuel by an air preheating combustor in which arelatively small part of the total fuel is burned. The preheatingcombustor operates at a relatively low temperature to avoid productionof nitrogen oxides, and thus may produce some carbon monoxide. This,however, is burned in the main reaction zone, which operates at a highertemperature. Prevaporization of the fuel eliminates hot spots caused byfuel droplet combustion and thus promotes clean combustion.

The fuel vaporizer comprises structure defining two concentric annularpassages through which the air flows with swirl and in which the fuel islaid on the outer wall of each passage from a circumferential manifold.Fuel may be supplied to one or both manifolds.

9 Claims, 4 Drawing Figures Sheet 1 0f 2 US. Patent Dec. 9, 1975 QQQRZDUUS. Patent Dec. 9, 1975 Sheet 2 of2 3,925,002

AIR PREHEATING COMBUSTION APPARATUS My invention is directed tocombustion apparatus of a type suitable for use in gas turbine enginesand particularly to a combustion apparatus employing combustion of aminor part of the fuel in a precombustor which brings all of the primaryor combustion air for the main combustor to a temperature high enoughfor successful vaporization of fuel delivered into it within a fuelvaporizer through which the primary air proceeds to a main reaction zonewhere the major part of the fuel is burned.

The combustion apparatus according to the invention is particularlyintended for use with engines of a non-regenerative type in which thecombustion air is at whatever temperature results from the compressionof the air, without additional heating in a regenerator or recuperatorby exhaust gases.

It is well known that a great deal of effort has been put into devisingcombustion apparatus for power plants of all sorts to produce exhaustgases with extremely low concentrations of products considered to beinimical to public health such as smoke, unburned hydrocarbons, carbonmonoxide, and oxides of nitrogen. One promising avenue toward such cleancombustion lies in vaporization of the liquid hydrocarbon fuel andmixture of the vapor with the combustion air prior to the actualcombustion of the fuel in the air. This is relatively easy in an engineof a regenerative type in which the air entering the combustionapparatus is ordinarily at about 500 to 600C. However, my invention isdirected to cleaning the exhaust of a known type of non-regenerativesingle-shaft gas turbine engine, the Allison Model 501 engine. Thisengine, in various models, is used for aircraft propulsion, instationary power plants for gas pumping and generation of electricity,and for propulsion of boats. A typical Model 501 engine has a poweroutput of 4680 shaft horsepower under static sea level conditions and1084C. turbine inlet temperature. The engine has a compression ratio of9.2 to 1.v

Fuel is burned in six combustion liners arranged in parallel relation inan annular combustion air space to which air is delivered by thecompressor. The general arrangement of combustion liners in the engineis as shown in McDowall et al. US. Pat. No. 2,729,938, Jan. 10, 1956,and Tomlinson US. Pat. No. 3,064,424, Nov. 20, 1962. Rated air flow is14.65 kilograms per second or about 2.45 kilograms per second througheach combustion liner.

According to my invention, the relatively low temperature compressordischarge air supplied to the combustion apparatus of the engine isheated to about 500 to 650C. in an air preheating combustor associatedwith each main combustion liner, the air so heated flows through fuelvaporization apparatus in which fuel is vaporized and mixed with thecombustion air so supplied, and the resulting mixture is burned in amain combustion zone of the apparatus. Thereafter, it flows through thedilution zone of the combustion apparatus where additional unheatedcompressed air is mixed with the combustion products to bring theturbine motive fluid to the desired temperature.

While the invention is described here in terms of application to aparticular engine, it will be obvious that the principles of theinvention may be applied to en gines of various sizes and pressureratios, and with other different parameters.

The principal objects of my invention are to provide a clean burningcombustion apparatus, to provide a combustion apparatus in which air forfuel vaporization is preheated prior to vaporization of the fuel andentry of the resulting mixture into a main reaction zone; to provideimproved fuel vaporization means for a combustion apparatus; and toprovide a combustion apparatus which is clean burning over a relativelywide range of power outputs.

The nature of my invention and its advantages will be apparent to thoseskilled in the art from the succeeding detailed description of thepreferred embodiment of the invention, the accompanying drawingsthereof, and the appended claims.

Referring to the drawings,

FIG. 1 is a schematic illustration of a combustion apparatusincorporating a combustion liner according to my invention.

FIG. 2 is an enlarged fragmentary sectional view taken on the planeindicated by the line 2--2 in FIG. 3.

FIG. 3 is a longitudinal sectional view of the combustion liner.

FIG. 4 is an enlargement of a portion of FIG. 3.

Referring first to FIG. 1, a combustion liner 2 according to theinvention is mounted within a housing or combustion outer case 3. Acompressor 4 delivers air under pressure into a space 6 defined betweenthe housing 3 and the exterior of the combustion liner 2. Fuel issupplied to the combustion liner through a fuel line 7 connected to afuel nozzle 8 which delivers fuel into a preheating combustor 10.

Additional fuel is supplied through lines 11 and 12 to a fuel vaporizer14. The combustion products from the preheating combustor 10 flowthrough the vaporizer 14 into main combustion apparatus 15 defined bythe downstream portion of the liner 2. The combustion products from themain combustion apparatus are discharged through an outlet 16 andthrough suitable transition ducting (not illustrated) into the turbineof the gas turbine engine, which drives the compressor 4.

Referring now to FIG. 3, the fuel atomizing nozzle 8 enters the upstreamend of the preheating combustor 10 where it is surrounded by an airinlet swirler 18 which preferably is a part of the fuel nozzle assembly.The preheating combustor 10 is enclosed by a wall of circular crosssection defining a dome 19 at the upstream end, a reaction zone sidewall 20, and a diverging dilution and outlet section 22. The fuelvaporizer l4 begins at the downstream end of wall section 22. It isenclosed by a cylindrical wall portion 23 and a converging downstreamwall portion 24 which ends at the beginning of the main combustionapparatus 15. This combustion apparatus is enclosed by an annularforward wall 26 and a side wall portion 27 which provides the outer wallof the main reaction zone 28 in which combustion of the fuel iscompleted. The reaction zone is connected through a slightly convergingwall section 30 to a liner wall section 31 which encloses the dilutionzone 32 and terminates at the outlet 16. The combustion liner may besupported at nozzle 8 by an outer swirler 34 mounted on the swirler l8and by suitable supports at the discharge end of the liner, as iscommon. Suitable ignition apparatus and cross connections betweencombustion liners (not illustrated) may be provided generally as shownin the McDowall et al patent cited above.

The preheating combustor 10 is generally similar to conventional gasturbine combustion liners except for the fact that it is proportioned tooperate on a low overall fuel-air ratio so as to discharge combustionproducts at about 600C, much below the inlet temperature of a gasturbine. In addition to the combustion air entering through swirlers 18and 34, combustion air enters through a ring of six ports 35 distributedaround the forward portion of wall 20. I prefer that about 40% ofpreheater combustion air enter through the swirlers and 60% throughports 35. Combustion takes place in the usual manner, and dilution airto mix with the combustion products is admitted through six ports 36near the downstream end of wall section 20 and six ports 38 in theupstream end of diverging wall section 22. Air entering radially throughdilution air ports 36 and 38 mixes with the combustion products fromburning of the fuel discharged by nozzle 8. The combustion products thenare discharged through an annular outlet 39 into the fuel vaporizer 14.

The fuel vaporizer includes a wall 40 defining with the outer wallportions 23 and 24 an annular passage 42 of approximately constant area.Wall 40 is supported from wall 23 by a ring of swirl vanes 43 whichswirl the air flowing into the passage 42. Vanes 43 terminate at a sheetmetal ring 44 abutting the inner surface of wall 23. The downstream endof wall 40 is welded to a wall 46 which defines the outer boundary of asecond annular passage 47 of approximately constant area. A ring 48 isfixed to the upstream ends of walls 40 and 46. The inner boundary ofpassage 47 is defined by a converging wall 51 supported from wall 46 bya swirler 52. Swirler 52 (see also FIG. 2) comprises an annular cascadeof vanes 54 extending between an outer ring 55 abutting wall 46 and aninner ring 56 abutting wall 51.

Wall 51 forms part of a centerbody 58 which, in addition to the sidewall 51, has a forward wall 59 and a downstream end wall 60. Thestructure providing the two passages 42 and 47 through the fuelvaporizer has now been described.

Introduction of fuel is accomplished from a manifold 62 on the outersurface of wall section 23 and a manifold 63 on the outer surface ofwall 46. These are connected to a source of fuel through the fuel lines11 and 12 already referred to. Each manifold delivers fuel to the innersurface of the wall on which it is mounted through a ring of small holeswhich discharge onto the inner surface of the wall just downstream ofthe ring 44 or 55, respectively. Eighteen approximately tangential fuelholes 64 evenly spaced around the axis of the apparatus are machinedthrough the wall 46 and 26 similar holes are machined through the wall23. Fuel thus discharged onto the inner surfaces of the walls iscontacted by the hot air coming through the swirler immediately upstreamfrom the fuel delivery point, evaporated, and mixed with the air. It isthen discharged through the downstream ends of the coaxial passages 42and 47. The two streams merge in the outlet from the fuel vaporizer anddischarge into the reaction zone 28 through the central opening 66 inwall 26. It should be noted that this opening is slightly smaller thanthe diameter of the discharge end of the vaporizer so that the innermostportion of the wall serves as a flow dam to promote turbulence andmixing. Due to the swirl around the liner axis. the fuel-air mixturetends to recirculate in a generally toroidal pattern in the reactionzone, and the fuel burns after being lit off by any suitable igniter.

No combustion air is added in the reaction zone. The reaction zone wall27 is cooled by convection by structure of a type previously known. Airto cool the side wall 27 flows between the outer surface of this walland the inner surface of a sleeve 67 which is supported adjacent theouter surface of wall 27 by axially extending strips 68 spacedcircumferentially around the wall. As shown more clearly in FIG. 4, apassage 70 for convection cooling air is defined between the walls 27and 67. This is closed at the downstream end by a ring 71 disposedbetween the walls, and the cooling air is discharged into the combustionliner through a ring of holes 72. A baffle 74 fixed to the wall 27deflects this air downstream along the inner surface of the wall portion30 for film cooling of this wall.

Dilution air is admitted to the dilution zone 32 through a ring of eightsecondary air ports 76. The resulting mixture with the combustionproducts from the main combustion zone constitutes the motive fluiddeveloped by the combustor.

It may be desirable to indicate typical dimensions of a combustion linersuch as that shown. FIG. 3 is a drawing to scale of a linerapproximately 15 centimeters in diameter. Primary ports 35 areapproximately 13 millimeters in diameter, and ports 36 and 38 areapproximately 20 millimeters in diameter. Fuel inlet ports 64 and thecorresponding ports through wall 23 are about 4 millimeters in diameter.The fuel ports should be large enough so that the fuel may be admittedwithout any considerable pressure drop or without going in at highvelocity.

The fabrication of the combustion apparatus may follow usual techniqueswith the parts being formed to shape and welded or brazed together.

Considering now the preferred mode of operation of the combustionapparatus and referring again to FIG. 1, we discuss specifically anengine operating normally at constant speed and air flow, with fuel flowvaried to vary engine power output through variation of turbine inlettemperature. Fuel for the pilot or preheater fuel nozzle 8 and for themain fuel manifolds 62 and 63 may be drawn from a fuel supply line 78 bya pump 79 which may be driven by the engine. The pump delivers fuelthrough a fuel control 80 to an engine metered fuel line 82. Fuelcontrol 80 determines the rate of supply of fuel to the engine andreturns excess fuel through a return line 83. Metered fuel line 82branches into the lines 7, 11, and 12 previously referred to. Divisionof flow between the several lines is suitably controlled. Asillustrated, a valve 84 controls flow through line 7, a valve 85controls flow through line 11, and a valve 86 controls flow through line12. Fuel is supplied con stantly to the pilot or preheat fuel nozzle 8.Valve 84 may be a flow-limiting valve limiting flow to about 30% ofmaximum power fuel flow. At idle (substantially zero shaft power) andpower levels above that, fuel is supplied to the fuel manifold 62through valve 85. This may be a valve responsive to the pressure aheadof valve 84 which opens at a predetermined value of this pressure andcontinues to open as flow increases through line 82 with increasingengine power level. The manifold 63 is fueled only at higher powerlevels of the engine. This flow may be controlled by a valve 86 whichopens in response to increased fuel pressure level at higher fuel flowlevels.

Any other suitable arrangement for sequencing or controlling flow to themanifolds may be used. Many such are known in connection with duplexfuel nozzles or with zone burning arrangements in jet engineafterburners. for example. My invention is not concerned i with thedetails of valving or fuel supply, which may be as required to suit theoperating environment of the engine. Valves such as 84, 85, and 86 maycontrol flow to a number of combustion liners in parallel.

In the operation of the combustor, it is contemplated that about of fullpower fuel will be injected through nozzle 8 so as to preheat the airdelivered to the vaporizer to about 600C. Since a rather large amount ofair is admitted through the ports 35, 36, and 38, the resultingcombustion products are cool and airrich. The combustion zone in thepreheating combustor is conventional and will have hot spots, fueldroplets, and the usual deficiencies of conventional combustors.However, the NO, contribution from this zone is low due to the smallamount of total fuel (20%) admitted in the preheat zone. The lowcombustion temperature and short residence time may cause some exhaustof carbon monoxide or unburned hydrocarbons from the preheatingcombustor, but these are duly oxidized in the main combustion zone 28where temperature will rise to about l400 to l650C. Because ofcombustion with a premixed mass may vaporized fuel and air, there isclean combustion, avoiding hot spots, in the main reaction zone,minimizing combination of oxygen with nitrogen. The preheating combustordoes not require any variable geometry; that is, means for varying theair flow split. If found desirable, means such as are well known maay beprovided to throttle flow through the main dilution air ports 76 to varythe ratio of primary to secondary air in the main combustion apparatus.

The structure, mode of operation, and advantages of combustion apparatusaccording to the invention should be apparent to those skilled in theart from the foregoing description. 7

The detailed description of the preferred embodiment of the inventionfor the purpose of explaining the principles thereof is not to beconsidered as limiting or restricting the invention, since manymodifications may be made by the exercise of skill in the art.

I claim:

1. A combustion apparatus for a gas turbine engine or the likecomprising, in combination, a housing adapted to receive air underpressure and a combustion liner in the housing; the combustion linerhaving an upstream end and a downstream outlet end and defining, in flowsequence from the upstream end to the downstream end, an air preheatingcombustor, a fuel vaporizer, a main reaction zone, and a main dilutionzone; the air preheating combustor comprising a preheat reaction zonehaving means for admitting preheat combustion air and fuel and a preheatdilution zone having means for admitting dilution air and mixing thedilution air with the combustion air from the preheat reaction zone toprovide at least substantially all combustion air for the main reactionzone, in combination with means to proportion the fuel and air so as todischarge a combustion products and air mixture from the preheatingcombustor at approximately 600 Celsius into the fuel vaporizer; the fuelvaporizer comprising means defining a passage leading from thepreheating combustor to the main reaction zone, and means for deliveringfuel into the said passage for evaporation and mixture with the gasesflowing through the said passage; and the main dilution zone definingentrances for dilution air by-passing the preheating combustor.

2. A combustion apparatus for a gas turbine engine or the likecomprising, in combination, a housing adapted to receive air underpressure and a combustion liner in the housing; the combustion linerhaving an upstream end and a downstream outlet end and defining, in flowsequence from the upstream end to the downstream end, an air preheatingcombustor, a fuel vaporizer, a main reaction zone, and a main dilutionzone; the air preheating combustor comprising a preheat reaction zonehaving means for admitting preheat combustion air and fuel and a preheatdilution zone having means for admitting dilution air and mixing thedilution air with the combustion air from the preheat reaction zone toprovide at least substantially all combustion air for the main reactionzone, in combination with means to proportion the fuel and air so as todischarge a combustion products and air mixture from the preheatingcombustor at approximately 600 Celsius into the fuel vaporizer; the fuelvaporizer comprising means defining a passage leading from thepreheating combustor to the main reaction zone and means for deliveringfuel into the said passage for evaporation and mixture with the gasesflowing through the said passage; the preheat dilution zone divergingdownstream and the fuel vaporizer converging downstream to an outletinto the main reaction zone; the main reaction zone diverging abruptlyfrom the fuel vaporizer outlet; and the main dilution zone definingentrances for dilution air bypassing the preheating combustor.

3. A combustion apparatus for a gas turbine engine or the likecomprising, in combination, a housing adapted to receive air underpressure and a combustion liner in the housing; the combustion linerhaving an upstream end and a downstream outlet end and defining, in flowsequence from the upstream end to the downstream end, an air preheatingcombustor, a wall film fuel vaporizer, a main reaction zone, and a maindilution zone; the air preheating combustor comprising a preheatreaction zone having means for admitting preheat combustion air and fueland a preheat dilution zone having means for admitting dilution air andmixing the dilution air with the combustion air from the preheatreaction zone to provide all combustion air for the main reaction zone,in combination with means to proportion the fuel and air so as todischarge a combustion products and air mixture from the preheatingcombustor at approximately 600 Celsius into the fuel vaporizer; the fuelvaporizer comprising wall means defining an annular passage leading fromthe preheating combustor to the main reaction zone, means for impartingswirl to the gases flowing through the said passage, means fordelivering fuel to the outer wall of the said passage for evaporationand mixture with the gases flowing through the said passage.

4. A combustion apparatus for a gas turbine engine or the likecomprising, in combination, a housing adapted to receive air underpressure and a combustion liner in the housing; the combustion linerhaving an upstream end and a downstream outlet end and defining, in flowsequence from the upstream end to the downstream end, an air preheatingcombustor, a wall film fuel vaporizer, a main reaction zone, and a maindilution zone; the air preheating combustor comprising a preheatreaction zone having means for admitting preheat combustion air and fueland a preheat dilution zone having means for admitting dilution air andmix ing the dilution air with the combustion air from the preheatreaction zone to provide all combustion air for the main reaction zone,in combination with means to proportion the fuel and air so as todischarge a combustion products and air mixture from the preheatingcombustor at approximately 600 Celsius into the fuel vaporizer; the fuelvaporizer comprising wall means defining an annular passage leading fromthe preheating combustor to the main reaction zone, means for impartingswirl to the gases flowing through the said passage, means fordelivering fuel to the outer wall of the said passage for evaporationand mixture with the gases flowing through the said passage, the preheatdilution zone diverging downstream and the fuel vaporizer convergingdownstream to an outlet into the main reaction zone; and the mainreaction zone diverging abruptly from the fuel vaporizer outlet.

5. A combustion apparatus for a gas turbine engine or the likecomprising, in combination, a housing adapted to receive air underpressure and a combustion liner in the housing; the combustion linerhaving an upstream end and a downstream outlet end and defining, in flowsequence from the upstream end to the downstream end, an air preheatingcombustor, a wall film fuel vaporizer, a main reaction zone, and a maindilution zone; the air preheating combustor comprising a preheatreaction zone having means for admitting preheat combustion air and fueland a preheat dilution zone having means for admitting dilution air andmixing the dilution air with the combustion air from the preheatreaction zone to provide all combustion air for the main reaction zone,in combination with means to proportion the fuel and air so as todischarge a combustion products and air mixture from the preheatingcombustor at approximately 600 Celsius into the fuel vaporizer; the fuelvaporizer comprising wall means defining outer and inner annularpassages leading in parallel from the preheating combustor to the mainreaction zone, means for imparting swirl to the gases flowing throughthe said passages, means for delivering fuel to the outer walls of thesaid passages for evaporation and mixture with the gases flowing throughthe said passages, and means for routing fuel alternatively to one orboth of said passages. I

6. A combustion apparatus for a gas turbine engine or the likecomprising, in combination, a housing adapted to receive air underpressure and a combustion liner in the housing; the combustion linerhaving an upstream end and a downstream outlet end and defining, in flowsequence from the upstream end to the downstream end, an air preheatingcombustor, a wall film fuel vaporizer, a main reaction zone, and a maindilution zone; the air preheating combustor comprising a preheatreaction zone having means for admitting preheat combustion air and fueland a preheat dilution zone having means for admitting dilution air andmixing the dilution air with the combustion air from the preheatreaction zone to provide all combustion air for the main reaction zone,in combination with means to proportion the fuel and air so as todischarge a combustion products and air mixture from the preheatingcombustor at approximately 600 Celsius into the fuel va' porizer; thefuel vaporizer comprising wall means defining outer and inner annularpassages leading in parallel from the preheating combustor to the mainreaction zone, means for imparting swirl to the gases flowing throughthe said passages, means for delivering fuel to the outer walls of thesaid passages for evaporation and mixture with the gases flowing throughthe said passages, and means for routing fuel alternatively to one orboth of said passages; the preheat dilution zone 8 diverging downstreamand the fuel vaporizer converging downstream to an outlet into the mainreaction zone; the main reaction zone diverging abruptly from the fuelvaporizer outlet.

7. A combustion apparatus for a gas turbine engine or the likecomprising, in combination, a housing adapted to receive air underpressure and a combustion liner in the housing; the combustion linerhaving an upstream end and a downstream outlet end and defining, in flowsequence from the upstream end to the downstream end, an air preheatingcombustor, a wall film fuel vaporizer, amain reaction zone, and a maindilution zone; the air preheating combustor comprising a preheatreaction zone having means for admitting preheat combustion air and fueland a preheat dilution zone having means for admitting dilution air andmixing the dilution air with the combustion air from the preheatreaction zone to provide all combustion air for the main reaction zone,in combination with means to proportion the fuel and air so as todischarge a combustion products and air mixture from the preheatingcombustor at approximately 600 Celsius into the fuel vaporizer; the fuelvaporizer comprising wall means defining outer and inner annularpassages leading in parallel from the preheating combustor to the mainreaction zone, means for imparting swirl to the gases flowing throughthe said passages, means for delivering fuel to the outer walls of thesaid passages for evaporation and mixture with the gases flowing throughthe said passages, and means for routing fuel alternatively to one orboth of said passages; the preheat dilution zone diverging downstreamand the fuel vaporizer converging downstream to an outlet into the mainreaction zone; the main reaction zone diverging abruptly from the fuelvaporizer outlet; means for convectively cooling the liner wall portionbounding'the reaction zone by air flowing to the main dilution zone; andthe main dilution zone defining entrances for dilution air by-passingthe preheating combustor.

8. A method of burning liquid hydrocarbon fuel in compressed combustionair comprising burning and mixing in the air a portion of the fuelsufficient to produce a mixture of air and combustion products at about600 Celsius in a first zone; flowing the said mixture into a second zoneand evaporating the remainder of the fuel in the mixture in the secondzone; flowing the resulting mixture of air, combustion products, andfuel into a third zone; and completing combustion of the fuel in the airin the said resulting mixture in the third zone.

9. A method of burning liquid hydrocarbon fuel in compressed combustionair to provide motive fluid for an engine comprising burning and mixingin the air a portion of the fuel sufficient to produce a mixture of airand combustion products at about 600 Celsius in a first zone; flowingthe said mixture into a second zone and evaporating the remainder of thefuel in the mixture in the second zone; flowing the resulting mixture ofair, combustion products, and fuel into a third zone; and completingcombustion of the fuel in the air in the said resulting mixture in thethird zone; flowing the resulting product into a fourth zone; and mixingdilution air with the said resulting product in the fourth zone toprovide motive fluid for an engine.

1. A combustion apparatus for a gas turbine engine or the likecomprising, in combination, a housing adapted to receive air underpressure and a combustion liner in the housing; the combustion linerhaving an upstream end and a downstream outlet end and defining, in flowsequence from the upstream end to the downstream end, an air preheatingcombustor, a fuel vaporizer, a main reaction zone, and a main dilutionzone; the air preheating combustor comprising a preheat reaction zonehaving means for admitting preheat combustion air and fuel and a preheatdilution zone having means for admitting dilution air and mixing thedilution air with the combustion air from the preheat reaction zone toprovide at least substantially all combustion air for the main reactionzone, in combination with means to proportion the fuel and air so as todischarge a combustion products and air mixture from the preheatingcombustor at approximately 600* Celsius into the fuel vaporizer; thefuel vaporizer comprising means defining a passage leading from thepreheating combustor to the main reaction zone, and means for deliveringfuel into the said passage for evaporation and mixture with the gasesflowing through the said passage; and the main dilution zone definingentrances for dilution air by-passing the preheating combustor.
 2. Acombustion apparatus for a gas turbine engine or the like comprising, incombination, a housing adapted to receive air under pressure and acombustion liner in the housing; the combustion liner having an upstreamend and a downstream outlet end and defining, in flow sequence from theupstream end to the downstream end, an air preheating combustor, a fuelvaporizer, a main reaction zone, and a main dilution zone; the airpreheating combustor comprising a preheat reaction zone having means foradmitting preheat combustion air and fuel and a preheat dilution zonehaving means for admitting dilution air and mixing the dilution air withthe combustion air from the preheat reaction zone to provide at leastsubstantially all combustion air for the main reaction zone, incombination with means to proportion the fuel and air so as to dischargea combustion products and Air mixture from the preheating combustor atapproximately 600* Celsius into the fuel vaporizer; the fuel vaporizercomprising means defining a passage leading from the preheatingcombustor to the main reaction zone and means for delivering fuel intothe said passage for evaporation and mixture with the gases flowingthrough the said passage; the preheat dilution zone diverging downstreamand the fuel vaporizer converging downstream to an outlet into the mainreaction zone; the main reaction zone diverging abruptly from the fuelvaporizer outlet; and the main dilution zone defining entrances fordilution air by-passing the preheating combustor.
 3. A combustionapparatus for a gas turbine engine or the like comprising, incombination, a housing adapted to receive air under pressure and acombustion liner in the housing; the combustion liner having an upstreamend and a downstream outlet end and defining, in flow sequence from theupstream end to the downstream end, an air preheating combustor, a wallfilm fuel vaporizer, a main reaction zone, and a main dilution zone; theair preheating combustor comprising a preheat reaction zone having meansfor admitting preheat combustion air and fuel and a preheat dilutionzone having means for admitting dilution air and mixing the dilution airwith the combustion air from the preheat reaction zone to provide allcombustion air for the main reaction zone, in combination with means toproportion the fuel and air so as to discharge a combustion products andair mixture from the preheating combustor at approximately 600* Celsiusinto the fuel vaporizer; the fuel vaporizer comprising wall meansdefining an annular passage leading from the preheating combustor to themain reaction zone, means for imparting swirl to the gases flowingthrough the said passage, means for delivering fuel to the outer wall ofthe said passage for evaporation and mixture with the gases flowingthrough the said passage.
 4. A combustion apparatus for a gas turbineengine or the like comprising, in combination, a housing adapted toreceive air under pressure and a combustion liner in the housing; thecombustion liner having an upstream end and a downstream outlet end anddefining, in flow sequence from the upstream end to the downstream end,an air preheating combustor, a wall film fuel vaporizer, a main reactionzone, and a main dilution zone; the air preheating combustor comprisinga preheat reaction zone having means for admitting preheat combustionair and fuel and a preheat dilution zone having means for admittingdilution air and mixing the dilution air with the combustion air fromthe preheat reaction zone to provide all combustion air for the mainreaction zone, in combination with means to proportion the fuel and airso as to discharge a combustion products and air mixture from thepreheating combustor at approximately 600* Celsius into the fuelvaporizer; the fuel vaporizer comprising wall means defining an annularpassage leading from the preheating combustor to the main reaction zone,means for imparting swirl to the gases flowing through the said passage,means for delivering fuel to the outer wall of the said passage forevaporation and mixture with the gases flowing through the said passage,the preheat dilution zone diverging downstream and the fuel vaporizerconverging downstream to an outlet into the main reaction zone; and themain reaction zone diverging abruptly from the fuel vaporizer outlet. 5.A combustion apparatus for a gas turbine engine or the like comprising,in combination, a housing adapted to receive air under pressure and acombustion liner in the housing; the combustion liner having an upstreamend and a downstream outlet end and defining, in flow sequence from theupstream end to the downstream end, an air preheating combustor, a wallfilm fuel vaporizer, a main reaction zone, and a main dilution zone; theair preheating combustor comprising a preheat reaction zone having meansfor admitting pReheat combustion air and fuel and a preheat dilutionzone having means for admitting dilution air and mixing the dilution airwith the combustion air from the preheat reaction zone to provide allcombustion air for the main reaction zone, in combination with means toproportion the fuel and air so as to discharge a combustion products andair mixture from the preheating combustor at approximately 600* Celsiusinto the fuel vaporizer; the fuel vaporizer comprising wall meansdefining outer and inner annular passages leading in parallel from thepreheating combustor to the main reaction zone, means for impartingswirl to the gases flowing through the said passages, means fordelivering fuel to the outer walls of the said passages for evaporationand mixture with the gases flowing through the said passages, and meansfor routing fuel alternatively to one or both of said passages.
 6. Acombustion apparatus for a gas turbine engine or the like comprising, incombination, a housing adapted to receive air under pressure and acombustion liner in the housing; the combustion liner having an upstreamend and a downstream outlet end and defining, in flow sequence from theupstream end to the downstream end, an air preheating combustor, a wallfilm fuel vaporizer, a main reaction zone, and a main dilution zone; theair preheating combustor comprising a preheat reaction zone having meansfor admitting preheat combustion air and fuel and a preheat dilutionzone having means for admitting dilution air and mixing the dilution airwith the combustion air from the preheat reaction zone to provide allcombustion air for the main reaction zone, in combination with means toproportion the fuel and air so as to discharge a combustion products andair mixture from the preheating combustor at approximately 600* Celsiusinto the fuel vaporizer; the fuel vaporizer comprising wall meansdefining outer and inner annular passages leading in parallel from thepreheating combustor to the main reaction zone, means for impartingswirl to the gases flowing through the said passages, means fordelivering fuel to the outer walls of the said passages for evaporationand mixture with the gases flowing through the said passages, and meansfor routing fuel alternatively to one or both of said passages; thepreheat dilution zone diverging downstream and the fuel vaporizerconverging downstream to an outlet into the main reaction zone; the mainreaction zone diverging abruptly from the fuel vaporizer outlet.
 7. Acombustion apparatus for a gas turbine engine or the like comprising, incombination, a housing adapted to receive air under pressure and acombustion liner in the housing; the combustion liner having an upstreamend and a downstream outlet end and defining, in flow sequence from theupstream end to the downstream end, an air preheating combustor, a wallfilm fuel vaporizer, a main reaction zone, and a main dilution zone; theair preheating combustor comprising a preheat reaction zone having meansfor admitting preheat combustion air and fuel and a preheat dilutionzone having means for admitting dilution air and mixing the dilution airwith the combustion air from the preheat reaction zone to provide allcombustion air for the main reaction zone, in combination with means toproportion the fuel and air so as to discharge a combustion products andair mixture from the preheating combustor at approximately 600* Celsiusinto the fuel vaporizer; the fuel vaporizer comprising wall meansdefining outer and inner annular passages leading in parallel from thepreheating combustor to the main reaction zone, means for impartingswirl to the gases flowing through the said passages, means fordelivering fuel to the outer walls of the said passages for evaporationand mixture with the gases flowing through the said passages, and meansfor routing fuel alternatively to one or both of said passages; thepreheat dilution zone diverging downstream and the fuel vaporizerconverging dowNstream to an outlet into the main reaction zone; the mainreaction zone diverging abruptly from the fuel vaporizer outlet; meansfor convectively cooling the liner wall portion bounding the reactionzone by air flowing to the main dilution zone; and the main dilutionzone defining entrances for dilution air by-passing the preheatingcombustor.
 8. A method of burning liquid hydrocarbon fuel in compressedcombustion air comprising burning and mixing in the air a portion of thefuel sufficient to produce a mixture of air and combustion products atabout 600* Celsius in a first zone; flowing the said mixture into asecond zone and evaporating the remainder of the fuel in the mixture inthe second zone; flowing the resulting mixture of air, combustionproducts, and fuel into a third zone; and completing combustion of thefuel in the air in the said resulting mixture in the third zone.
 9. Amethod of burning liquid hydrocarbon fuel in compressed combustion airto provide motive fluid for an engine comprising burning and mixing inthe air a portion of the fuel sufficient to produce a mixture of air andcombustion products at about 600* Celsius in a first zone; flowing thesaid mixture into a second zone and evaporating the remainder of thefuel in the mixture in the second zone; flowing the resulting mixture ofair, combustion products, and fuel into a third zone; and completingcombustion of the fuel in the air in the said resulting mixture in thethird zone; flowing the resulting product into a fourth zone; and mixingdilution air with the said resulting product in the fourth zone toprovide motive fluid for an engine.